Probe card and method for producing the same

ABSTRACT

A probe card is used in conducting a visual test for a target test object through simultaneous contact of the probe card with each and every electrode pad of the target test object. The probe card includes a plurality of probes composed of conductive wire strands and having elastically deformable contact parts so curved as to make contact with electrode pads of a target test object. The contact parts are oriented in one and the same direction and extend in a parallel relationship with one another. The probe card further includes a first insulating block for fixedly securing one end parts of the probes, a second insulating block for fixedly securing the other end parts of the probes and a mounting plate for holding the first and second insulating blocks in such a manner that the contact parts of the probes protrude outwardly.

FIELD OF THE INVENTION

The present invention is directed to a probe card and a method forproducing the same, and more specifically to a probe card for use inconducting a visual test for a target test object through simultaneouscontact of the probe card with each and every electrode pad of thetarget test object and a method for producing such a probe card.

BACKGROUND OF THE INVENTION

In the field of manufacturing flat-panel displays such as a thin-filmtransistor-liquid crystal display (TFT-LCD), a plasma display panel(PDP), an organic electroluminescence (OEL) and the like, a panel isproduced through the use of a glass substrate and electrode pads and, inthe final test stage of a cell process, the entire electrode pads of adata/gate line are brought into simultaneous contact with a probe cardor a probe unit at a probing station. Electric signals are then appliedto the electrode pads of the data/gate line through the probe card tothereby test the electrical property thereof, which is referred to as avisual test.

Turning to semiconductor chips, they are manufactured through a numberof steps, including steps of producing a wafer, inspecting the wafer andpackaging a die. The wafer inspecting step is carried out by what iscalled an electrical die sorting inspection that tests the semiconductorchips for their electrical property. In the electrical die sortinginspection, a probe card is brought into direct contact with electrodepads of each of the semiconductor chips at a probing station, afterwhich electrical signals are applied to the electrode pads to conductthe electrical property test. Depending on the test results, thesemiconductor chips are sorted into qualified products and defectiveproducts.

As an example of prior art probing tools, a probe card is composed of anarray of small-sized metal needle probes. The needle probes are causedto make contact with electrode pads of a target test object, e.g., apanel of flat-panel displays or a semiconductor chip. Subsequently,electrical signals are applied to through the needle probes to test theelectrical connection of the electrode pads.

With the needle type probe card known in the art, each of the metalneedle probes can make contact with the corresponding electrode pad at acontact point of reduced size and hence the probe card may beadvantageously employed in testing objects with high density electrodepads. However, due largely to the fact that the needle probes are ofcantilever type, the smaller the diameter of the individual probes, theweaker the force by which the probes can be pressed against theelectrode pads. This involves a problem in that no stable contact can bemaintained between the probes and the electrode pads. Another problemposed by the needle type probe card is that, if the narrowlyspaced-apart probes are subject to flexural deformation, a short-circuitmay arise between the probes thus causing a fatal damage to the electriccircuits of the object tested.

Moreover, the task of uniformly aligning the individual probes in theprocess of producing the prior art probe card has heretofore beenperformed by manual operations of a worker, which reduces theproductivity and the degree of precision of the products.

In recent years, a need exists to form solder balls on a semiconductorchip in advance of conducting a test. During the course of testing thesemiconductor chip with solder balls, however, the probes tend to beslipped from the solder balls, thus making it difficult to conduct thetest and shortening the life span of the probes.

As another example of the prior art probing tools, a probe card has beenproposed of the type comprising an insulating sheet and a plurality ofelongated leads disposed on the insulating sheet. A metallic material isplated and built up on the insulating sheet in an effort to miniaturizethe pitch of the leads. Attached to one side of the insulating sheet isa holder from which terminals of the insulating sheet and rear terminalsof the leads extend. The leads have front terminals which are flexurallydeformed under pressure to make contact with electrode pads of asemiconductor chip in a resiliently yieldable manner.

The lead type probe card is disadvantageous in that the leads areunevenly built up by plating and therefore have no uniform thickness,thereby resulting in poor contact between the leads of the probe cardand the electrode pads of an object tested. In addition, the leads arebonded to the insulating sheet in a small area, as a result of which thefront terminals of the leads may be separated from the insulating sheetwhen the insulating sheet and the leads are subject to repeated flexuraldeformation.

As a further example of the prior art probing tools, there has beenproposed a probe card that is provided with blade-type probes. Theblade-type probes are fabricated by forming slits in an insulator madeof, e.g., ceramics, and fitting tips into the slits. The task of fittingthe tips is conducted manually by a worker, which is disadvantageous interms of the productivity and the production costs. Furthermore, theprobes of this type are cumbersome and inconvenient to change.

SUMMARY OF THE INVENTION

Taking into account the above and other problems inherent in the priorart probe cards, it is an object of the present invention to provide aprobe card that, while exhibiting excellent durability and improvedreliability, can enhance elastic deformability of individual conductiveprobes and accommodate positional errors between the probes andelectrode pads of a target test object, thereby assuring stabilized andreliable contact of the probes with the electrode pads.

Another object of the present invention is to provide a probe card whoseindividual probes can be produced, fitted and changed with ease, thusenabling the probe card to be produced with increased productivity andreduced production costs.

A further object of the present invention is to provide a probe cardthat can positively prevent occurrence of short-circuit betweenindividual probe cards through the use of simple and easy-to-forminsulating means.

A still further object of the present invention is to provide a methodfor producing a probe card whereby a probe card having enhancedreliability can be produced with increased productivity and reducedcosts.

With these objects in view, according to one aspect of the presentinvention, there is provided a probe card, comprising: a plurality ofprobes composed of conductive wire strands and having elasticallydeformable contact parts so curved as to make contact with electrodepads of a target test object, the contact parts oriented in one and thesame direction and extending in a parallel relationship with oneanother; a first insulating block for fixedly securing one end parts ofthe probes; a second insulating block for fixedly securing the other endparts of the probes; and a mounting plate for holding the first andsecond insulating blocks in such a manner that the contact parts of theprobes protrude outwardly from between the first and second insulatingblocks.

According to another aspect of the present invention, there is provideda probe card, comprising: a plurality of probes composed of conductivethin plates and extending in a parallel relationship with one anotherfor avoidance of short-circuit, each of the probes having first andsecond contact parts at its top opposite sides and first and secondcoupling recesses at its bottom opposite sides; first and second supportbases respectively coupled with the first and second coupling recesses;an insulating means for preventing the probes from short-circuiting; andfirst and second embracing plates provided at opposite ends of the firstand second support bases for pressing the probes against one another.

According to a further aspect of the present invention, there isprovided a method for producing a probe card, comprising the steps of:aligning a plurality of conductive wire strands in a parallelrelationship with one another in such a manner as to avoid occurrence ofshort-circuit; fixedly securing one end parts of the conductive wirestrands to a first insulating block; fixedly securing the other endparts of the conductive wire strands to a second insulating block sothat intermediate parts of the conductive wire strands can extendbetween the first and second insulating blocks; attaching the firstinsulating block to a mounting plate; crushing the intermediate parts ofthe conductive wire strands in their longitudinal directions to formcurved contact parts; and attaching the second insulating block to themounting plate in a spaced-apart relationship with respect to the firstinsulating block.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become apparent from the following description of apreferred embodiment given in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a block diagram showing an example of a probing station thatincorporates a probe card according to the present invention;

FIG. 2 is a perspective view showing a probe card in accordance with afirst embodiment of the present invention;

FIGS. 3 a through 3 c are front views showing individual probes employedin a probe card according to a first embodiment of the present;

FIG. 4 is a flowchart illustrating a method for producing a probe cardaccording to a first embodiment of the present;

FIG. 5 is a perspective view showing an exemplary method of aligningconductive wire strands in a method for producing a probe card accordingto a first embodiment of the present;

FIG. 6 is a perspective view showing a probe card in accordance with asecond embodiment of the present invention;

FIG. 7 is a perspective view showing a probe card in accordance with athird embodiment of the present invention;

FIG. 8 is a partially cut away sectional view showing a probe card inaccordance with a third embodiment of the present invention;

FIG. 9 is a perspective view showing a probe card in accordance with afourth embodiment of the present invention;

FIG. 10 is a perspective view showing one exemplary method of aligningconductive wire strands on an insulating film in order to produce aprobe card according to a fourth embodiment of the present;

FIG. 11 is a perspective view showing another exemplary method ofaligning conductive wire strands on an insulating film in order toproduce a probe card according to a fourth embodiment of the present;

FIG. 12 is a perspective view showing a probe card in accordance with afifth embodiment of the present invention;

FIG. 13 is a perspective view showing a probe card in accordance with afifth embodiment of the present invention, with probes separated frominsulating sheets; and

FIG. 14 is a perspective view showing a probe card in accordance with asixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of a probe card according to the present inventionand a method for producing the same will now be described in detail withreference to the accompanying drawings.

Referring first to FIG. 1, there is shown an example of a probingstation that incorporates a probe card according to the presentinvention. As shown in FIG. 1, the probing station 10 is provided with aprobe card 20 according to the present invention which can be broughtinto contact with electrode pads of a target test object, e.g., a flatdisplay panel. The probe card 20 is connected to a tape carrier packageblock (TCP) 12 which in turn is connected to a pogo block 16 by means ofa connector 14. The pogo block 16 is connected to a main board 18. Theconnector 14 is composed of a flexible printed circuit. The pogo block16 denotes an interface board for transmitting signals between the mainboard 18 and the probe card 20 in the probing station. Although FIG. 1shows the probe card 20 as applied to an input side of the probingstation 10, it would be possible to apply the probe card 20 to an outputside thereof.

FIG. 2 shows a probe card in accordance with a first embodiment of thepresent invention. Referring to FIG. 2, the probe card 100 of the firstembodiment is provided with a plurality of probes 110 that can makecontact with, and apply electric signals to, electrode pads of a targettest object, e.g., a flat display panel or a semiconductor chip. Theprobes 110 are composed of elongated conductive wire strands 112.

Referring to FIGS. 3 a through 3 b, the conductive wire strands 112 areprovided with elastically deformable contact parts 114, 114 a, 114 b,114 c of varying configuration which can make direct contact with theelectrode pads of the target test object. The conductive wire strands112 may be made of, but are not limited to, metal, carbon fibers andother conductive materials. Depending on the circumstances, theconductive wire strands 112 may be either of solid type or hollow type.

As shown in FIG. 3 a, each of the conductive wire strands 112 is crushedin its longitudinal direction and partially curved to create anelastically deformable contact part 114 a of generally arcuate shape,with one end 116 a and the other end 116 b of the conductive wirestrands 112 left free. Each of the conductive wire strands 112 isfurther provided with a first straight part 118 a adjoining the one end116 a of the conductive wire strands 112 and a second straight part 118b adjoining the other end 116 b, both of which are of rectilinearconfiguration. The arcuate contact part 114 a is brought into contactwith the electrode pads of the target test object at its apex. Turningto FIG. 3 b, each of the conductive wire strands 112 is crushed in itslongitudinal direction and partially curved to create an elasticallydeformable contact part 114 b of generally triangular shape, with oneend 116 a and the other end 116 b of the conductive wire strands 112left free. Each of the conductive wire strands 112 is further providedwith a first straight part 118 a and a second straight part 118 b, bothof which are of rectilinear configuration. The triangular contact part114 b is brought into contact with the electrode pads of the target testobject at its apex.

Referring to FIG. 3 c, each of the conductive wire strands 112 ispartially bent to create an elastically deformable contact part 114 c ofgenerally loop shape, with one end 116 a and the other end 116 b of theconductive wire strands 112 left free. Each of the conductive wirestrands 112 is further provided with a first straight part 118 a and asecond straight part 118 b, both of which are in a parallel relationshipwith each other.

Referring again to FIG. 2, the first and second straight parts 118 a,118 b are respectively fixedly secured to a first insulating block 120and a second insulating block 130. The conductive wire strands 112extend between the first insulating block 120 and the second insulatingblock 130 in a spaced-apart relationship with one another for avoidanceof inadvertent short-circuit. The curved contact parts 114 of theconductive wire strands 112 protrude outwardly form between the firstand second insulating blocks 120, 130 and are oriented in one and thesame direction.

Each of the first and second insulating blocks 120, 130 are halved intoa first plate 122 or 132 and a second plate 124 or 134. Alternatelyformed on the first plate 122 or 132 are a plurality of channels 122 aor 132 a for receiving the first and second straight parts 118 a, 118 bof the conductive wire strands 112 and a plurality of ridge-like spacers122 b, 132 b for keeping the conductive wire strands 112 spaced apart.In the present embodiment, it would be possible to eliminate thechannels 122 a or 132 a and the ridge-like spacers 122 b, 132 b, ifneeded.

The second plate 124 or 134 of the first and second insulating blocks120, 130 is affixed to amounting plate 140. The conductive wire strands112, the second plate 124 or 134 of the first and second insulatingblocks 120, 130 and the mounting plate 140 are joined together by meansof a fastener means such as adhesive bonding, bolting, snap hooking orthe like.

Such conductive wire strands 112 are pre-stressed under a condition thatthe one end 116 a and the other end 116 b thereof are restricted, andtherefore serve as curved beams in terms of shape and two end-fixedbeams structurally, which type of beams exhibit increased flexuralstiffness and improved durability. This means that the contact parts 114of the conductive wire strands 112 are not susceptible to plasticdeformation when they are pressed against the electrode pads by avertically exerting load, while the contact area between the contactparts 114 and the electrode pads are increased so as to reduce electricresistance and heat generation.

Additionally, it becomes possible to reduce the cross-sectional area ofeach of the conductive wire strands 112 while maintaining the flexuralstiffness thereof at the same level as the conventional needle typeprobes. This assures that a probe card can be produced in conformitywith the electrodes of a target test object disposed at high density.Moreover, the contact parts 114 of the conductive wire strands 112 canbe elastically deformed in such a manner that they accommodatepositional errors between the conductive wire strands 112 and theelectrode pads. This assures stabilized contact between the contactparts 114 and the electrode pads and drastically improvescontact-keeping ability of the conductive wire strands 112, thus makingit possible to conduct the test in a reliable manner. It should beappreciated that the shape of the contact parts 114 may be changed toother suitable ones, although the contact parts 114 are shown anddescribed to have arcuate, triangular and loop configurations in thepresent embodiment.

With reference to FIG. 4, description will now be offered regarding amethod for producing a probe card in accordance with a first embodimentof the present invention.

Initially, a plurality of conductive wire strands 112 are aligned anddisposed in a spaced-apart parallel relationship with one another in afashion that no short-circuit can occur between the conductive wirestrands 112 (S100). The parts of the conductive wire strands 112adjoining one end 116 a thereof are disposed between first and secondplates 122, 124 of a first insulating block 120 and then fixedly securedto the first insulating block 120 (S102). The parts of the conductivewire strands 112 adjoining the other end thereof are disposed betweenfirst and second plates 132, 134 of a second insulating block 130 andthen fixedly secured to the second insulating block 130 while leavingfree intermediate parts (corresponding to contact parts 114 to be formedlater) of the conductive wire strands 112 (S104). During this process,first and second straight parts 118 a, 118 b of the conductive wirestrands 112 are respectively received in channels 122 a, 132 a of thefirst plates 122, 132.

At a next step, the first insulating block 120 is attached to one endside of the mounting plate 140 (S106). The intermediate parts of theconductive wire strands 112 are crushed in their longitudinal directionsto form curved contact parts 114, after which the second insulatingblock 130 is attached to the other end side of the mounting plate 140(S108) in a spaced-apart relationship with respect to the firstinsulating block 120. By way of the probe card production methodaccording to a first embodiment of the present invention, a probe card100 can be produced that comprises a plurality of probes 110 havingcontact parts 114 a of arcuate configuration or contact parts 114 b oftriangular configuration. It should be appreciated that the step ofcrushing the intermediate parts of the conductive wire strands 112 maybe performed in advance of the step of attaching the first insulatingblock 120 to one end side of the mounting plate 140.

In order to produce a probe card 100 with the use of probes 110 composedof conductive wire strands 112 having loop-shaped contact parts 114 c asshown in FIG. 3 c, first straight parts 118 a of the conductive wirestrands 112 are fixedly secured to a first insulating block 120 (seeFIG. 2) which in turn is attached to one end side of a mounting plate140. Then, second straight parts 118 b of the conductive wire strands112 are fixedly secured to a second insulating block 130 which in turnis attached either to the mounting plate 140 at the same side as thefirst insulating block 120 or to the first insulating block 120. Throughthis process, it becomes possible to produce a probe card composed ofconductive wire strands 112 whose opposite ends are restricted in such amanner as to pre-stress loop-shaped contact parts 114 c thereof. In thistype of probe card, the second straight parts 118 a, 118 b mayaltogether be secured either to the first insulating block 120 or thesecond insulating block 130.

Referring to FIG. 5, there is illustrated an exemplary manner wherebythe conductive wire strands 112 are aligned between, and fixedly securedto, the first and second plates 122, 124 of the first insulating block120 in the probe card production method according to a first embodimentof the present invention.

As shown in FIG. 5, an elongated conductive wire is wound in pluralturns around first and second spools 150, 152 spaced apart at apredetermined spacing in such a manner that a plurality of conductivewire strands 112 are aligned in a parallel relationship with oneanother. The conductive wire strands 112 thus extend rectilinearly andare spaced apart at a predetermined spacing.

The conductive wire strands 112 wound around the first and second spools150, 152 are interposed between, and fixedly secured to, the first andsecond plates 122, 124 of the first insulating block 120. It can be seenin FIG. 5 that two separate first insulating blocks 120 are employed toclamp upper and lower extensions of the conductive wire strands 112wound around the first and second spools 150, 152. Then, the conductivewire strands 112 secured to the first insulating block 120 are severedat their opposite end parts. In other words, the severing is conductedat one end parts of the conductive wire strands 112 contiguous to thefirst spool 150 and at the other end parts of the conductive wirestrands 112 contiguous to the second spool 152 so that intermediateparts can extend between the other end parts of the conductive wirestrands 112 and the first insulating block 120. In this manner, theconductive wire strands 112 can be precisely aligned and secured inplace by use of the first and second plates 122, 124 of the firstinsulating block 120. It would be possible to change the diameter of theconductive wire strands 112 by regulating the tensile force imparted tothe conductive wire strands 112.

FIG. 6 shows a probe card in accordance with a second embodiment of thepresent invention. Just like the probe card 100 of the first embodiment,a probe card 200 according to the second embodiment of the presentinvention comprises probes 210 composed of conductive wire strands 212,a first insulating block 220, a second insulating block 230 and amounting plate 240. The conductive wire strands 212 are provided withcontact parts 214 protruding outwardly from between the first and secondinsulating blocks 220, 230 in one and the same direction.

A plurality of insulating wire strands 260 are disposed in between theconductive wire strands 212 for avoidance of inadvertent short-circuit.The insulating wire strands 260 are made of, e.g., a resin-impregnatedwire (“SPECTRA” produced and sold by Honeywell Corp., U.S.A.) and anylon wire. As shown in FIG. 5, the conductive wire strands 212 and theinsulating wire strands 260 are alternately wound around the first andsecond spools 150, 152 in a mutually parallel relationship, after whichthey are interposed between and fixedly secured to a first plate 222 anda second plate 224 of the first insulating block 220. In order toincrease the density of the conductive wire strands 212, it is necessaryto wind the conductive wire strands 212 and the insulating wire strands260 on the first and second spools 150, 152 as closely as possible.

Referring collectively to FIGS. 5 and 6, in a method for producing aprobe card according to a second embodiment, one of upper and lowerextensions of the conductive wire strands 212 and the insulating wirestrands 260 extending between the first and second spools 150, 152 arefixedly secured to between the first and second plates 222, 224 of thefirst insulating block 220. Subsequently, the conductive wire strands212 and the insulating wire strands 260 secured to the first insulatingblock 220 are severed at their opposite end parts. More specifically,the severing is conducted at one end parts of the conductive wirestrands 212 and the insulating wire strands 260 contiguous to the firstspool 150 and at the other end parts thereof contiguous to the secondspool 152 so that intermediate parts can extend between the other endparts and the first insulating block 220.

Then, the other end parts of the conductive wire strands 212 and theinsulating wire strands 260 are fixedly secured to between the first andsecond plates 232, 234 of the second insulating block 230. The firstinsulating block 220 is attached to one end side of the mounting plate240. The intermediate parts of the conductive wire strands 212 and theinsulating wire strands 260 are crushed in their longitudinal directionsto form curved contact parts 214 on the conductive wire strands 212,after which the second insulating block 230 is attached to the other endside of the mounting plate 240 in a spaced-apart relationship withrespect to the first insulating block 220. By way of attaching the firstand second blocks 220, 230 to the opposite end sides of the mountingplate 240, the elastically deformable contact parts 214 are created onintermediate parts of the conductive wire strands 212 between the firstand second blocks 220, 230. The same curved parts as the contact parts214 of the conductive wire strands 212 are formed on the insulating wirestrands 260.

FIGS. 7 and 8 show a probe card in accordance with a third embodiment ofthe present invention. Just like the probe cards 100, 200 of the firstand second embodiments, a probe card 300 according to the thirdembodiment of the present invention comprises probes 310 composed ofconductive wire strands 312, a first insulating block 320, a secondinsulating block 330 and a mounting plate 340. The conductive wirestrands 312 are provided with contact parts 314 protruding outwardlyfrom between the first and second insulating blocks 320, 330 in one andthe same direction.

An insulating layer 360 is coated on the entire surface of theconductive wire strands 312 except for the contact spots 314 a of thecontact parts 314 which would make contact with electrode pads of atarget test object. The step of coating the insulating layer 360 on theconductive wire strands 312 is carried out in advance of forming thecontact parts 314. The contact parts 314 are formed before or during thetime when the first and second insulating blocks 320, 330 are attachedthe mounting plate 340. Then, a part of the insulating layer 360 isremoved from the contact parts 314 to create the contact spots 314 a, asshown in FIG. 8. Removal of the insulating layer 360 can be done bychemical etching, knife cutting, grinding or the like. In the presentinvention, the conductive wire strands 312 on which the insulating layer360 is coated may be made of, e.g., gold, silver or copper wire that hasbeen used as a bonding wire for the purpose of connecting asemiconductor circuit.

The probe card 300 composed of the conductive wire strands 312 havingthe insulating layer 360 are advantageous in disposing the probes 310 ata closer spacing as compared to the probe cards 100, 200 of the firstand second embodiments described above. As a result, it becomes possibleto dispose the probes 310 with extremely high density in the probe card300 of the third embodiment.

FIG. 9 shows a probe card in accordance with a fourth embodiment of thepresent invention. Just like the probe cards 100, 200, 300 of the firstthrough third embodiments, a probe card 400 according to the fourthembodiment of the present invention comprises probes 410 composed ofconductive wire strands 412, a first insulating block 420, a secondinsulating block 430 and a mounting plate 440. The conductive wirestrands 412 are provided with contact parts 414 protruding outwardlyfrom between the first and second insulating blocks 420, 430 in one andthe same direction.

An insulating film 470 is provided between the conductive wire strands412 and the second plates 424, 434 of the first and the secondinsulating blocks 420, 430. The insulating film 470 has an adhesivelayer 472 on its surface that makes contact with the conductive wirestrands 412. The conductive wire strands 412 are disposed on and bondedto the adhesive layer 472 of the insulating film 470 in a mutuallyspaced-apart parallel relationship. The opposite end parts of theconductive wire strands 412 and the insulating film 470 are fixedlysecured to between the first and second plates 422, 424 of the firstinsulating block 420 and the first and second plates 432, 434 of thesecond insulating block 430 in such a manner that intermediate parts canextend between the first and second insulating blocks 420, 430. Thefirst insulating block 420 is attached to one end side of the mountingplate 440. The intermediate parts of the conductive wire strands 412 arecrushed in their longitudinal directions to form curved contact parts414 on the conductive wire strands 212, after which the secondinsulating block 430 is attached to the other end side of the mountingplate 440 in a spaced-apart relationship with respect to the firstinsulating block 420. Thus, the probe card 400 of the fourth embodimentis produced. As in the second embodiment, it would be possible todispose a plurality of insulating wire strands between the conductivewire strands 412. It would be also possible that, as in the thirdembodiment, an insulating layer is coated on the surface of theconductive wire strands 412.

With the probe card 400 of the fourth embodiment, the insulating film470 serves to reinforce the elastic deformability of the probes 410,thus enabling the contact parts 414 to make contact with electrode padsof a target test object in an accurate and stable manner. Furthermore,the conductive wire strands 412 can be kept spaced apart by way ofbonding the conductive wire strands 412 to the insulating film 470 andcrushing the conductive wire strands 412 to create the contact parts 414of curved shape.

Referring to FIG. 10, in order to dispose and bond the conductive wirestrands 412 on the adhesive layer 472 of the insulating film 470, theinsulating film 470 is wound around first and second spools 150, 152that are spaced apart at a predetermined spacing. Then, a conductivewire is wound over the adhesive layer 472 of the insulating film 470 toprovide the conductive wire strands 412 disposed in a parallelrelationship with one another. This ensures that the conductive wirestrands 412 are bonded to the adhesive layer 472 of the insulating film470 at a uniform spacing. The mutually bonded conductive wire strands412 and insulating film 470 are then severed at their opposite end partsto acquire a sheet of insulating film 470 to which the conductive wirestrands 412 are bonded together.

The adhesive layer 472 of the insulating film 470 may be made of ahot-melt adhesive, in which case the conductive wire strands 412 arewound around the adhesive layer 472 while heating. It would be possibleto use a resin film with low melting point in place of the insulatingfilm 470 having the adhesive layer 472. In order to have the conductivewire strands 412 bonded to such a resin film, the conductive wirestrands 412 should be coated by an adhesive or otherwise the conductivewire strands 412 of naked condition should be wound over the resin filmunder heating. In case of using the conductive wire strands 412 whosesurface is coated with an insulating layer, the conductive wire strands412 can be bonded to the insulating film 470 by melting the insulatinglayer with heat or dissolving the insulating layer with chemicals.

FIG. 11 shows a exemplary method of aligning the conductive wire strandson the insulating film in order to produce the probe card according tothe fourth embodiment of the present. As shown, the insulating film 470is wound in multiple turns around a single spool 154 and the conductivewire strands 412 are wound over and bonded to the insulating film 470 ina mutually parallel relationship. The mutually bonded conductive wirestrands 412 and insulating film 470 are then severed in a directionparallel to the axis of the spool 154 to acquire a sheet of insulatingfilm 470 to which the conductive wire strands 412 are bonded together.

FIGS. 12 and 13 show a probe card in accordance with a fifth embodimentof the present invention. As shown in these drawings, the probe card 500of the fifth embodiment comprises a plurality of probes 510 composed ofconductive thin plates 512 of generally rectangular configuration. Eachof the conductive thin plates 512 has first and second contact parts 514a, 514 b at its top opposite sides and first and second couplingrecesses 516 a, 516 b at its bottom opposite sides. Moreover, each ofthe conductive thin plates 512 is provided at its longitudinal oppositeends with first and second cutouts 518 a, 518 b that serve todistinguish the conductive thin plates 512 from insulating sheets 530set forth below.

The first contact parts 514 a of the conductive thin plates 512 areadapted to make contact with electrode pads of a target test object tothereby apply electrical signals to the target test object therethrough.The second contact parts 514 b of the conductive thin plates 512 can beconnected to a tape carrier package block 12 of a probing station 10illustrated only in FIG. 1. First and second support bases 520, 522 arecoupled with the first and second coupling recesses 516 a, 516 b of theconductive thin plates 512.

Although the first and second coupling recesses 516 a, 516 b are ofsemicircular shape and the first and second support bases 520, 522 arecomposed of rods in the embodiment illustrated in FIG. 12, the couplingrecesses 516 a, 516 b and the support bases 520, 522 may have othershapes, e.g., polygonal configuration, if desired.

A plurality of insulating sheets 530 are disposed between the probes 510for the purpose of preventing occurrence of short-circuit. Each of theinsulating sheets 530 has first and second coupling recesses 532 a, 532b at its bottom opposite sides, which correspond to the first and secondsupport bases 520, 522. First and second embracing plates 540, 542 forpressing the probes 510 against one another are provided at oppositeends of the first and second support bases 520, 522. Each of the firstand second embracing plates 540, 542 has guide holes 540 a, 542 athrough which the first and second support bases 520, 522 are insertedto allow displacement of the embracing plates 540, 542 therealong. Thefirst and second embracing plates 540, 542 are affixed in place by afastener means not shown in the drawings.

With the probe card 500 of the fifth embodiment described above, if oneof the conductive thin plates 512 is damaged while in use, the user candisplace the first and second embracing plates 540, 542 outwardly alongthe first and second support bases 520, 522, thereby relieving thepressing force imparted to the conductive thin plates 512 and theinsulating sheets 530. This allows the user to separate the damaged oneof the conductive thin plates 512 away from the first and second supportbases 520, 522 and replace it with a new conductive thin plate. At thistime, the cutouts 518 a, 518 b formed at the longitudinal opposite endsof the insulating sheets 530 enables the user to distinguish theconductive thin plates 512 from the insulating sheets 530, thusimproving the convenience in the process of changing the conductive thinplates 512.

FIG. 14 shows a probe card in accordance with a sixth embodiment of thepresent invention. As shown, a probe card 600 of the sixth embodimentcomprises a plurality of probes 610, first and second support bases 620,622, and first and second embracing plates 640, 642, all of which aresubstantially the same as the corresponding components of the probe card500 according to the fifth embodiment.

The probes 610 are composed of conductive thin plates 612. Each of theconductive thin plates 612 has first and second contact parts 614 a, 614b at its top opposite sides and first and second coupling recesses 616a, 616 b at its bottom opposite sides. First and second support bases620, 622 are coupled with the first and second coupling recesses 616 a,616 b of the conductive thin plates 612. First and second embracingplates 640, 642 for pressing the probes 610 against one another areprovided at opposite ends of the first and second support bases 620,622.

An insulating layer 630 is provided on one major flank surface of eachof the conductive thin plates 612 except for the first and secondcontact parts 614 a, 614 b. The insulating layer 630 may be either aninsulating tape bonded to the conductive thin plates 612 or aninsulating material coated on the conductive thin plates 612. In thelatter case, the insulating material is first coated on one entiresurface of each of the conductive thin plates 512 and those parts of thecoated insulating material corresponding to the first and second contactparts 614 a, 614 b are removed by chemical etching, knife cutting,grinding or the like. In an effort to improve productivity, it would bepossible to produce the probes 610 by way of cutting a wide metal sheetwith an insulating layer into a plurality of plate pieces through waterjet cutting, press forming or the other suitable cutting methods.

The probe card 600 of the sixth embodiment having the conductive thinplates 612 coated with the insulating layer 630 is simple in structureand can be produced with increased productivity and in a cost-effectivemanner, as compared to the probe card 500 of the fifth embodiment thatmakes use of the insulating sheets 530 to provide insulation between theprobes 510.

As described in the foregoing, in accordance with the present invention,it becomes possible to provide a probe card that, while exhibitingexcellent durability and improved reliability, can enhance elasticdeformability of individual conductive probes and accommodate positionalerrors between the probes and electrode pads of a target test object tothereby assure stabilized and reliable contact the probes with theelectrode pads. Furthermore, individual probes can be produced, fittedand changed with ease, thus enabling a probe card to be produced withenhanced productivity and reduced production costs. In addition, theprobe card can positively prevent occurrence of short-circuit betweenindividual probe cards through the use of simple and easy-to-forminsulating means. According to a probe card production method of thepresent invention, a probe card having enhanced reliability can beeasily produced with increased productivity and reduced costs.

Although certain preferred embodiments of the present invention havebeen described in detail, it will be apparent to those skilled in theart that various changes or modifications may be made thereto within thescope of the invention defined by the appended claims.

1. A probe card, comprising: a plurality of probes composed ofconductive wire strands and having elastically deformable contact partsso curved as to make contact with electrode pads of a target testobject, the contact parts oriented in one and the same direction andextending in a parallel relationship with one another; a firstinsulating block for fixedly securing one end parts of the probes; asecond insulating block for fixedly securing the opposite end parts ofthe probes; and a mounting plate for holding the first and secondinsulating blocks in such a manner that the contact parts of the probesprotrude outwardly from between the first and second insulating blocks;wherein the conductive wire strands are in a pre-stressed state.
 2. Theprobe card as defined in claim 1, wherein the contact parts of theconductive wire strands are elastically deformable, without beingsusceptible to plastic deformation, under a vertically applied load. 3.The probe card as defined in claim 1, wherein the contact parts of theconductive wire strands, when pressed against the electrode pads of thetarget test object by a vertically applied load, are elasticallydeformable, without being susceptible to plastic deformation, so as toenlarge a contact area between the contact parts and the electrode pads.4. The probe card as defined in claim 1, wherein the opposite end partsof each of the probes are placed one upon another so as to shape thecontact part between said opposite end parts as a loop.
 5. A probe card,comprising: a plurality of probes composed of conductive wire strands,the wire strands having first end parts, second end parts andelastically deformable intermediate contact parts so curved as to makecontact with electrode pads of a target test object, the intermediatecontact parts oriented in one and the same direction and extending in aparallel relationship with one another; and means for fixedly holdingthe first and second end parts of the conductive wire strands in such amanner that the intermediate contact parts protrude in one directionfrom between the first and second end parts of the conductive wirestrands; wherein the conductive wire strands are pre-stressed with thefirst and second end parts being restricted.
 6. The probe card asdefined in claim 5, wherein the intermediate contact parts of theconductive wire strands are elastically deformable, without beingsusceptible to plastic deformation, when pressed against the electrodepads of the target test object by a vertically applied load.
 7. Theprobe card as defined in claim 5, wherein the intermediate contact partsof the conductive wire strands, when pressed against the electrode padsof the target test object by a vertically applied load, are elasticallydeformable, without being susceptible to plastic deformation, so as toenlarge a contact area between the intermediate contact parts and theelectrode pads.
 8. The probe card as defined in claim 5, wherein theintermediate contact part of each of the conductive wire strands isloop-shaped while the respective first and second end parts are placedone upon another.